Blower for breathing apparatus

ABSTRACT

This invention relates to a blower for a breathing apparatus. The blower comprising a bottom support with a stub axle, a top support with a stub axle, a motor core comprising a motor stator and rotor, and an impeller coupled to the motor core via a shaft, the shaft is rotatably coupled at a first end to the stub axle on the top support and at a second end via the stub axle on the bottom support.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Field of the Invention

The present invention relates to a reduced foot-print blower, preferablyfor use in breathing apparatus such as CPAP breathing apparatus.

Background

Blowers are used in a range of breathing apparatus applications, andalso other applications.

SUMMARY

It is an object of the present invention to provide a smaller blower.This enables the blower to be used in a range of applications wherelower weight, inertia and/or size are desirable, such as in portable,body/head mounted and/or miniaturised breathing apparatus.

In one aspect the invention may comprise a blower for a breathingapparatus comprising: a bottom support with a stub axle, a top supportwith a stub axle, a motor core comprising a motor stator and rotor, animpeller coupled to the motor core via a shaft, wherein the shaft isrotatably coupled at a first end to the stub axle on the top support andat a second end via the stub axle on the bottom support.

Optionally the shaft is rotatably coupled at the first and second endsto the stub axles by bearings in the shaft.

Optionally the stub axle is compliant and/or resilient.

Optionally the shaft is partially or fully hollow and the first andsecond ends have bearings within the hollow.

Optionally each bearing comprises an inner race and an outer race, andeach stub axle couples to the respective inner bearing race.

Optionally the shaft maximum diameter size is independent of the bearingdiameter size.

Optionally the blower is an axial inlet/axial outlet blower.

Optionally the blower is a single stage axial inlet/axial outlet blower.

Optionally the impeller is integrally formed with the shaft or iscoupled via a press-fit.

Optionally the rotor or magnet is press-fit on the shaft.

In another aspect the present invention may comprise a blower for abreathing apparatus comprising: a housing, a motor core within thehousing, an impeller coupled to the rotor via a shaft, an airflowstator, wherein the impeller rotates within a region within the housingand directs outlet air axially through the airflow stator ring.

Optionally there is no volute.

Optionally the housing comprises a lower housing with a region for themotor and one or more apertures for axially receiving inlet air.

Optionally the blower is single stage.

Optionally the ratio of the impeller diameter to housing diameter is atleast about 90%.

In another aspect the present invention may comprise a blower for abreathing apparatus comprising: a housing, a motor core within thehousing, an impeller coupled to the rotor via a shaft, wherein theimpeller comprises: a hub, blades extending from the hub, and stubblades supported between the blades.

Optionally an annular ring extending around the blades and supportingthe stub blades.

Optionally the annular ring has an edge turned towards the outlet todirect outlet air axially.

Optionally the blower has:

-   -   a diameter of less than or equal to about 53 mm,    -   a height of less than or equal to about 21 mm, and/or    -   a weight of less than or equal to about 50 grams, or preferably        less than or equal to 47 grams and preferably 27 grams.

Optionally the impeller has:

-   -   a thickness of less than or equal to about 3 mm    -   a diameter of less than or equal to about 48 mm, or more        preferably 48.4 mm    -   a weight of less than or equal to about 3 grams

Optionally the impeller is integrally formed with the shaft or iscoupled via a press-fit.

Further aspects of the invention, which should be considered in all itsnovel aspects, will be described in the following description.

It should be noted that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications may be madewithout departing from the spirit and scope of the apparatus and systemsof the disclosure and without diminishing its attendant advantages. Forinstance, various components may be repositioned as desired. It istherefore intended that such changes and modifications be includedwithin the scope of the apparatus and systems of the disclosure.Moreover, not all of the features, aspects and advantages arenecessarily required to practice the present apparatus and systems ofthe disclosure. Accordingly, the scope of the present apparatus andsystems of the disclosure is intended to be defined only by the claimsthat follow.

Reference to any prior art in this specification is not, and should notbe taken as, an acknowledgement or any form of suggestion that thatprior art forms part of the common general knowledge in the field ofendeavour in any country in the world.

Wherein the foregoing description reference has been made to integers orcomponents having known equivalents thereof, those integers are hereinincorporated as if individually set forth.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike, are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense, that is to say, in the sense of“including, but not limited to”.

The apparatus and system of the disclosure may also be said broadly toconsist in the parts, elements and features referred to or indicated inthe specification of the application, individually or collectively, inany or all combinations of two or more of said parts, elements orfeatures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of a low profile blower will now be described with referenceto the following drawings.

FIG. 1 shows a cross-sectional perspective view of a low-profile blowerwith an axial input and an axial output according to a first embodiment.

FIG. 2 shows a partial exploded view of the low-profile blower.

FIG. 3 shows a cross-sectional perspective view of a low-profile blower,with two axial inlets and an axial output according to a secondembodiment.

FIG. 4 shows a cross-sectional perspective view of a low-profile blower,with an axial inlet and an axial output according to a third embodiment.

FIGS. 5 and 6 show another embodiment of an impeller that can be usedwith any of the previous embodiments.

FIG. 7 shows two alternative stub axle and bearing arrangements.

FIGS. 8 to 11 show cross-sectional and perspective view of a low-profileblower, with an axial inlet and radial outlet according to a fourthembodiment.

FIGS. 12A to 12C show various configurations of the stub axle, bearingsand shaft that could be used in variations.

FIGS. 13A to 13C show various inlet/outlet configurations of the blowerthat could be used in variations.

FIRST EMBODIMENT

FIGS. 1 and 2 shows one embodiment of single-stage axial inlet/axialoutlet blower (also called flow generator or fan). The low-profileblower is for use, for example, as a flow generator of a CPAP apparatus,high flow therapy apparatus or any other breathing apparatus.Alternatively, it can be used for any other suitable application.

The blower 10 comprises a bottom housing portion (“lower housing”) 11.The lower housing is formed as an annular wall 12 with an internalannular shelf 13. Radial ribs 14 extend from the underneath from theannular shelf (or pan). The ribs are formed as wall portions 14 a thathave radial arms 14 b extending from a lower portion that meet at acentral (lower) hub 15. This forms a recessed region (“sub-housing”) 20(see FIG. 2) between the ribs 14, 13 annular shelf and the lower hub 15for receiving a motor core 4 comprising a motor stator 16 and rotor 17.The lower housing 11/lower hub 15 act as a bottom/lower support for themotor stator 16, and at least a partial support for a bearing, which inturn provides support for the rotor 17 and an impeller 18 assembly. Theapertures or gaps between ribs 14 provide an axial inlet for air flow“A”. This provides motor cooling also.

The blower 10 also comprises a top housing portion (“upper housing”) 19,which sits on the lower housing 11. The upper housing comprises a topplate 21 (internal lid) with a central boss forming an upper hub 22. Anairflow ring 23 encircles the top plate. The airflow ring comprises anannular perimeter (outer annular wall) 24 with a rebate 24 a (see FIG.2) that sits on and couples to the top of the annular wall 12 of thelower housing 11; and an inner annular wall 25. This could be by way ofbayonets, bumps, snap fits, glue, ultrasonic or friction welding, or anyother suitable means. Curved channels e.g. 26 (see FIG. 2) are formedbetween the inner and outer annular walls for receiving and slowingairflow from the impeller 18 to create pressure. The upper housing actsas a top/upper support for the rotor and impeller assembly via a bearing28.

Note, while the terms “upper”, “lower”, “top”, “bottom” and the like areused throughout this specification, it will be appreciated that thoseterms are just relative terms used for referencing the drawings. Theactual blower in use might be orientated differently, and so referencesto vertical positions herein should not be considered limiting, andshould not be considered to refer to or limit the actual orientation ofthe blower and its components.

The motor core 4 comprises the motor stator 16 and rotor 17. The motorstator is supported on the radial arms 14 b of the ribs 14 in thesub-housing 20. They could be friction fitted, over moulded or glued tothe sub-housing 20, for example. The motor stator 16 comprises anannularly stacked laminated core 16 a with a toroidal winding 16 b. Therotor comprises a toroidal magnet 17 a coupled to a shaft 27. The magnetcould be coupled with a friction fit to the shaft, or coupled via overmoulding or gluing. The lower end of the shaft 27 has an annular rebate27 a (see FIG. 2) with an external diameter commensurate with the innerdiameter of the annular magnet 17 a for receiving the annular magnet.The shaft 27 is a cylindrical tube in the form of a bearing tube. Abearing e.g. 28 is disposed in the bearing tube at each end. The bearingcan have a friction fit with the shaft 27, or can be coupled via overmoulding or gluing. Reference numerals refer to the top bearing 28, butthese are equally applicable to the bottom bearing. Each bearing racecomprises an outer annular bearing race/housing 28 a, an inner annularbearing race/housing 28 b and ball or roller bearings 28 c movabletherebetween in a cage. As one non-limiting example, the bearings canhave an outside diameter of about 4 mm to 8 mm, an inside diameter ofabout 1.5 mm to 3 mm and a thickness of about 2 mm to 4 mm. The outerbearing race 28 a rotates relative to the inner bearing race 28 b. Theinner bearing race can remain stationary. In alternatives, a planebearing or bushing could be used instead. The shaft 27 is simplysupported between the upper housing 19 and the lower housing 11. Boththe upper housing and the lower housing comprise stub axles 29 a, 29 bin the form of compliant and/or resilient protrusions that extend intoand couple to the bearing races 28 a, 28 b of the respective bearings ateach end of the shaft. Preferably, the stub axles could be solid and/orrigid and are over moulded with a resilient and/or flexible material,such as silicone. Alternatively, the stub axles are formed from anelastomer (e.g. silicone) or other compliant and/or resilient material,and have a friction fit within the respective bearing races.Alternatively, the stub axles could be solid.

Each of the stub axles extend to a distal end from respective upper andlower housings. The stub axles extend towards each other. Each of thestub axles are substantially cylindrically shaped. In other embodiments,one or both of the stub axles taper or decrease in diameter as theyextend away from their respective upper and lower housings. The distalend of each stub axle is rounded. However, in other embodiments, thedistal end of one or both of the stub axles is substantially flat. Eachstub axle also comprises a shoulder that is formed by a flange orstepped portion. In other embodiments, the shoulder formed by a taper inthe stub axle. The shoulder is located at or near a proximal end of eachstub axle to the respective housing from which it extends. Upper andlower bearings engage the shoulder or respective stub axles to limitaxial movement of the bearing arrangement away from the shaft. The shaftalso has a shoulder formed at each end in an opposed relationship toeach respective stub axle shoulder. Each shaft shoulder is formed as arecess or stepped portion in an internal surface of the shaft. In otherembodiments, the shaft shoulder is formed by a taper in the internalsurface of the shaft. The upper and lower bearings also engagerespective shaft shoulders so that they are gripped between a shoulderon the shaft and a shoulder on a stub axle. The shaft/stub axle/bearingarrangement enables the shaft to be rotatably supported/coupled in asimply supported manner to the upper/lower housing.

The outer diameter of the outer bearing race 28 a could be about 4 mm,for example. The hollow shaft could have a commensurate diameter ofabout 4 mm to allow for a snug fit of the bearing race 28 a. The outershaft size in the rebate 27 a could be about 5 mm.

The impeller 18 can be coupled onto (e.g. press fit) or integrallyformed with the shaft 27, or integrally formed or over moulded or gluedonto the shaft. The impeller is shown in FIG. 2. The shaft can be ofsimilar diameter to the shaft in traditional topologies, which allowsfor robust mechanical coupling of the impeller and the magnet. Becausethe bearings are fitted on the inside of the shaft, the diameter of theshaft is not dictated by the inner diameter of the bearings. The outerdiameter of the shaft can then be a suitable size to allow for a robustimpeller coupling, e.g. about 5 mm, or alternatively from about 3 mm toabout 5 mm. A larger diameter shaft can still be used without dictatingthe bearing diameter size, because the bearings are internal to theshaft, the size of the bearing (e.g. the diameter size) can be selectedbased on acceptable bearing speed. For example, a smaller bearing can beused which is capable of higher RPM because the diameter is smaller andtherefore the balls are not moving in the race as quickly as they wouldbe for a large bearing. Using a smaller bearing enables higher RPMbecause smaller bearings are generally rated for higher RPM. Theimpeller is shown in FIG. 2. The impeller is also shown in FIGS. 5 and 6in more detail. Similarly, the magnet/rotor 17 a/17 is pressed onto theshaft. Similar advantages apply here, where the shaft can be a suitablesize to allow for robust coupling. The impeller 18 comprises a hubportion 5 and flat forward swept (full-length) blades (sometimes called“vanes”) 6, which radially extend from and connect to the hub portion.(Alternatively, the blades could be backward swept or radial). Eachblade comprises a vertical flat portion extending from the hub. Anannular rib/ring 7 is formed into the blades 6 and extends between themto provide rigidity at the perimeter of the blades. The ring curvestowards the outlet 7 a to provide rigidity to the blades and also directairflow through the airflow stator to be described later. A plurality ofshort stub (partial-length) blades 8 (also termed “splitter blades”)that extend part-way to the hub are interspaced between the full lengthblades 6. Each of the stub blades are also forward swept in theillustrated embodiment. The annular rib 7 is formed into and extendsbetween the stub blades 8, thus supporting them. The stub blades provideadditional pressure normally achieved with additional blades, withoutthe requirement for material to extend to the hub which reduces airspace at the hub. Reducing airspace at hub reduces the maximum flowcapability of the blower 10. If the number of blades is too high (andtherefore there is too little air space at the hub due to too manyblades), inlet flow is occluded, which restricts the outlet airflow ofthe blower.

In the impeller as shown in FIGS. 5 and 6 there are three stub bladesbetween each pair of full length blades 6. However, it will beappreciated that other numbers of sub blades 8 are possible. For examplethere may be between 1 and 7 stub blades or between 3 and 5 stub blades,or 1, 2, 3, 4 or 5 stub blades. In the illustrated embodiments of FIGS.3 and 5, the stub blades 8 are of different lengths. A middle orintermediate stub blade of each group of stub blades between adjacentfull length blades is longer than the adjacent stub blades (i.e. thestub blades to either side of the middle stub blade of that group ofstub blades). The side stub blades are of approximately the same length.Despite the different lengths, peripheral ends of all of the stub bladesin each group are disposed the same distance radially around theimpellor. This means that the interior end of the longer, middle stubblade is disposed radially closer to the centre of the impellor than theinterior end of each of the side stub blades. Peripheral ends of all ofthe stub blades and the full length blades are also disposed the samedistance radially around the impellor. Each of the stub blades aretapered towards their interior ends. That is, each of the stub bladesreduces in height towards their interior ends. To achieve this tapereach of the stub blades has a convex top edge. Hence, each of the stubblades are narrower at their interior ends relative to their peripheralends.

Material properties and construction techniques dictate that it isadvantageous to increase the blade count when pumping liquids because oftheir higher density. For example, the rotation rate (Hz) is multipliedby the number of blades to determine the blade pass frequency. Humanhearing is sensitive to tonal inputs between 300 Hz and 15 kHz and ifnot melodious, it is classified as noise. High frequency sound waves areeasier to attenuate than low frequency noise. Typical CPAP blowers haverotational speeds of around 180 revolutions per second. It is thereforeadvantageous to increase the blade count to improve attenuationcharacteristics. Unequal, dissimilar and prime numbers like 7, 11, 13,17, 19 and 23 help to reduce common fraction interactions between rotorand motor stator. As another example, decelerating a fluid by increasingthe flow area rapidly can result in boundary layer separation, flowreversals and turbulent losses. Pressure loss recovery via diffusionmechanisms dictate that the angle between blades should not exceed 12degrees. Dividing the full circumference (360 Degrees) by the sum of theblade thickness angle and the flow channel angle, a minimum blade numberfor optimal diffusion can be calculated. Adding more blades than optimalreduces the flow channel size with an increase in pressure drop.

But, increasing the blade count to distribute the force that a singleblade has to support and to aid noise reduction decreases the size ofthe flow channel through the impeller, which is disadvantageous. Thepresent inventors have overcome this issue by using stub/splitterblades. To minimise occlusion closer to the hub some blades may betruncated, referred to as splitter blades. Splitter blades could beplaced on a support disc or shrouds to transfer their part of the loadto the hub. But, blisks (bladed disks) and shrouded impellers have muchhigher rotational inertia. The present inventors have avoided this bysupporting the splitter blades on a rib 7 as described, which reducesinertia over a shroud or disc, and also minimises occlusion.

The motor is controlled using a power supply and a controller to rotatethe impeller to create the desired output air flow (both pressure and/orflow rate). Air is drawn through the apertures in the axial inlet by wayof the impeller, over the motor to provide cooling, and directed to theair flow stator via the impeller blades and ring. The air flow statorring slows the flow to create pressure, and the flow is directed axiallyout the airflow stator ring.

SECOND EMBODIMENT

FIG. 3 shows another embodiment of a single-stage axial inlet/axialoutlet blower. In this embodiment, there are two axial inlets, one atthe top of the motor and one at the bottom. Two inlets allows for asmaller inlet, which in turn allows for more effective blade length.There is also less noise associated with a smaller inlet.

The blower 50 comprises a top housing portion (“upper housing”) 51comprising a plate 51 a with an annular rim 51 b. At a central portionof the plate, a plurality of radial ribs 52 extend into a central(upper) hub 54 formed as a boss. The ribs create apertures 53 within theplate forming one axial air inlet into the blower 50. Air flow “B” goesinto the inlet during use. The blower also comprises a bottom housingportion (“lower housing”) 55. The lower housing is formed from anexternal annular wall 56 with a concentric internal annular stub wall 57a from which radially extends an annular shelf 57 b. Curved channels 57c are formed between the outer and inner annular walls to create anannular airflow stator ring 57 for receiving and slowing airflow fromthe impeller 27 to create pressure. Ribs 58 extend downwards from theedge of the annular shelf 57 b and then radially to meet at a central(lower) hub 59. This forms a recessed region (“sub-housing”) between theribs and annular shelf and the lower hub for receiving a motor core 4comprising a motor (core) stator 16 and rotor 17. The lowerhousing/lower hub acts as a bottom/lower support for a motor stator 16,and at least a partial support for a bearing, which in turn providessupport for a rotor and impeller assembly. The apertures formed betweenthe ribs provide another axial air inlet “A” into the blower. Thisprovides motor cooling also. Two smaller axial inlets (top and bottom)provide a larger effective blade length. The upper housing couples tothe top of the external annular wall of the lower housing. This could beby way of bayonets, bumps, snap fits, glue, ultrasonic or frictionwelding, or any other suitable means.

The motor core comprises the motor stator 16 and rotor 17. The motorstator is supported on the lower hub 59 in the sub-housing. The motorstator comprises a stacked laminated core with a toroidal winding. Therotor comprises an annular or toroidal magnet coupled to a shaft. Thelower end of the shaft has an annular rebate with an external diametercommensurate with the inner diameter of the annular magnet for receivingthe annular magnet. The shaft is a cylindrical tube in the form of abearing tube. A bearing, is disposed in the bearing tube at each end.Each bearing race comprises an outer annular bearing race/housing, aninner annular bearing race/housing and ball bearings therebetween. Asone non-limiting example, the bearings can have an outside diameter ofabout 4 mm to 8 mm, an inside diameter of about 1.5 mm to 3 mm and athickness of about 2 mm to 4 mm. The inner bearing race rotates relativeto the outer bearing race. In alternatives, a plane bearing or bushingcould be used instead. The shaft is simply supported between the upperhousing and the lower housing. Both the upper housing and the lowerhousing comprise stub axles in the form of compliant and/or resilientprotrusions that extend into and couple to the bearing races of therespective bearings at each end of the shaft. Preferably the stub axlesare formed from an elastomer (e.g. silicone) or other compliant and/orresilient material, and have a friction fit with the respective bearingraces. Alternatively, the stub axles could be solid and/or rigid and areover moulded with a resilient and/or flexible material. Alternatively,the stub axles could be solid. The stub axles may have any one or moreof the features described above in respect of the first embodiment.

The impeller can be coupled onto (e.g. press fit) or integrally formedwith the shaft. The shaft can be of similar diameter to the shaft intraditional topologies, which allows for robust mechanical coupling ofthe impeller. Because the bearings are fitted on the inside of theshaft, the diameter of the shaft is not dictated by the inner diameterof the bearings. The outer diameter of the shaft can then be a suitablesize to allow for a robust impeller coupling, e.g. about 5 mm, oralternatively from about 3 mm to about 5 mm. A larger diameter shaft canstill be used without dictating the bearing diameter size (leading toundesirably high bearing speeds), because the bearings are internal tothe shaft, the size of the bearing (e.g. the diameter size) can beselected based on acceptable bearing speed. The impeller is shown inFIG. 2. The impeller is also shown in FIGS. 5 and 6 in more detail.Similarly, the magnet/rotor 17 a/17 is pressed onto the shaft. Similaradvantages apply here, where the shaft can be a suitable size to allowfor robust coupling. The impeller comprises a hub portion and flatforward swept (full-length) blades, which radially extend from andconnect to the hub portion. (Alternatively, the blades could be backwardswept or radial). Each blade comprises a vertical flat portion extendingfrom the hub. An annular rib/ring 7 is formed into the blades 6 andextends between them to provide rigidity at the perimeter of the blades.The ring curves towards the outlet 7 a to provide rigidity to the bladesand also direct airflow through the airflow stator to be describedlater. A plurality of short stub (partial-length) blades 8 (also termed“splitter blades”) that extend part-way to the hub are interspacedbetween the full length blades 6. The annular rib is also formed intoand extends between the blades, thus supporting them. The stub bladesprovide additional pressure, without the requirement for material toextend to the hub which reduces air space at the hub. Reducing airspaceat hub reduces the maximum flow capability of the blower 10. If thenumber of blades is too high (and therefore there is too little airspace at the hub due to too many blades), inlet flow is occluded, whichrestricts the outlet airflow of the blower. The impellor may be inaccordance with the embodiments illustrated in FIGS. 5 and 6 and mayhave any one or more of the features described above in respect of thefirst embodiment.

This embodiment has the same advantages as described for the previousembodiment. It also has the further advantage of a dual axial inlet,providing for a less restrictive air inlet. It also provides motorcooling.

THIRD EMBODIMENT

FIG. 4 shows yet another embodiment 60 of single stage axial inlet/axialoutlet blower. This embodiment is similar to the previous embodiment,however, there is one axial inlet at the top of the motor.

The motor comprises a top housing portion (“upper housing”) 51comprising a plate 51 a with an annular rim 51 b. At a central portionof the plate, a plurality of ribs 52 extend into a central upper hub 54formed as a boss. The ribs create apertures 53 within the plate 51 aforming one axial air inlet into the blower 60. Air flow “B” goes intothe inlet during use. The blower also comprises a bottom housing portion(“lower housing”) 65. The lower housing is formed from an externalannular wall 66 with a concentric internal annular stub wall 67 a fromwhich radially extends an annular shelf 67 b. Curved channels 67 c areformed between the outer and inner annular walls to create an annularairflow stator ring 67 for receiving and slowing airflow from theimpeller 27 to create pressure. An annular wall 68 a extends downwardsfrom the edge of the annular shelf and then a floor 68 b extendsradially to meet at a central lower hub 69. This forms a recessed region(“sub-housing”) 68 between the wall and annular shelf and the lower hubfor receiving a motor core comprising the motor stator and rotor. Thelower housing/lower hub acts as a bottom/lower support for a motorstator, and at least a partial support a bearing which in turn providessupport for a rotor and impeller assembly. The upper housing couples tothe top of the external annular wall of the lower housing. This could beby way of bayonets, bumps, snap fits, glue, ultrasonic or frictionwelding, or any other suitable means.

The motor core comprises the motor stator and rotor. The motor stator issupported on the lower hub in the sub-housing. The motor statorcomprises an annular stacked laminated core with a toroidal winding. Therotor comprises an annular or toroidal magnet coupled to a shaft. Thelower end of the shaft has an annular rebate with an external diametercommensurate with the inner diameter of the annular magnet for receivingthe annular magnet. The shaft is a cylindrical tube in the form of abearing tube. A bearing, is disposed in the bearing tube at each end.Each bearing race comprises an outer annular bearing race/housing, aninner annular bearing race/housing and bearings therebetween. As onenon-limiting example, the bearings can have an outside diameter of about4 mm to 8 mm, an inside diameter of about 1.5 mm to 3 mm and a thicknessof about 2 mm to 4 mm. The inner bearing race rotates relative to theouter bearing race. In alternatives, a plane bearing or bushing could beused instead. The shaft is simply supported between the upper housingand the lower housing. Both the upper housing and the lower housingcomprise stub axles in the form of compliant and/or resilientprotrusions that extend into and couple to the bearing races of therespective bearings at each end of the shaft. Preferably the stub axlesare formed from an elastomer (e.g. silicone) or other compliant and/orresilient material, and have a friction fit with the respective bearingraces. Alternatively, the stub axles are solid and/or rigid and are overmoulded with a resilient and/or flexible material. Alternatively, thestub axles could be solid. The stub axles may have any one or more ofthe features described above in respect of the first embodiment.

The impeller can be coupled onto or integrally formed with the shaft.The shaft can be of similar diameter to the shaft in traditionaltopologies, which allows for robust mechanical coupling of the impeller.Because the bearings are fitted on the inside of the shaft, the diameterof the shaft is not dictated by the inner diameter of the bearings. Theouter diameter of the shaft can then be a suitable size to allow for arobust impeller coupling, e.g. about 5 mm, or alternatively from about 3mm to about 5 mm A larger diameter shaft can still be used withoutdictating the bearing diameter size (leading to undesirably high bearingspeeds), because the bearings are internal to the shaft, the size of thebearing (e.g. the diameter size) can be selected based on acceptablebearing speed. The impeller is shown in FIG. 2. The impeller is alsoshown in FIGS. 5 and 6 in more detail. Similarly, the magnet/rotor 17a/17 is pressed into the shaft. Similar advantages apply here, where theshaft can be a suitable size to allow for robust coupling. The impellercomprises a hub portion and flat forward swept (full-length) blades,which radially extend from and connect to the hub portion.(Alternatively, the blades could be backward swept or radial). Eachblade comprises a vertical flat portion extending from the hub. Anannular rib/ring 7 is formed into the blades 6 and extends between themto provide rigidity at the perimeter of the blades. The ring curvestowards the outlet 7 a to provide rigidity to the blades and also directairflow through the air flow stator to be described later. A pluralityof short stub (partial-length) blades 8 (also termed “splitter blades”)that extend part-way to the hub are interspaced between the full lengthblades 6. The annual rib is also formed into and extends between theblades, thus supporting them. The stub blades provide additionalpressure, without the requirement for material to extend to the hubwhich reduces air space at the hub. Reducing airspace at hub reduces themaximum flow capability of the blower 10. If the number of blades is toohigh (and therefore there is too little air space at the hub due to toomany blades), inlet flow is occluded, which restricts the outlet airflowof the blower. The impellor may be in accordance with the embodimentsillustrated in FIGS. 5 and 6 and may have any one or more of thefeatures described above in respect of the first embodiment.

This embodiment has the same advantages as described for the previousembodiment.

Another advantage of the resilient stub axles described in the aboveembodiments is that they accommodate misalignment of the connectionbetween the shaft and the bearings and enable pre-loading of thebearings.

In the embodiments described above, the shaft is hollow to allow thebearings to sit within the shaft at each end. In other embodiments, theshaft might only be partially hollow, but with sufficient space for thebearings to sit inside the shaft. For example, the shaft could haverecesses in each end for seating the bearings.

Referring to FIG. 7, in another alternative, the stub axles of theembodiments above might not extend through the bearings. Rather eachstub axle might only partially extend into (e.g. see stub axle 70), orjust contact (e.g. see stub axle 71) the bearing. These arrangementsstill provide sufficient support and allow for rotation.

FOURTH EMBODIMENT

FIGS. 8 to 10 show yet another embodiment 80 of a blower, this one beinga single stage axial inlet/radial outlet blower.

The blower 80 comprises a bottom housing portion (“lower housing”) 85.The lower housing is formed as a generally round body with a cylindricalside 85 a and a toroidal base portion 85 b forming part of an annularcollector 86 (for collecting flow from the impeller) and an inner motorregion 87 (see FIG. 10) concentric within the annular collector centre.The inner motor region is formed as a recess within the lower housing.An inner wall 86 a of the collector curves upwards to form the innermotor region 87. The inner motor region (“sub-housing”) 87 is forreceiving a motor core 88 assembly comprising the motor (core) stator 89and rotor 90. A central plate 91 with a central aperture is supported onthe inner collector wall 86 a. The plate is dimensioned with an annulargap 92 between the plate perimeter 93 and the inner cylindrical sidewall 85 a to define a top impeller region 94 in the housing body 85. Theannular gap 92 provides an air flow path 96 from an impeller 95 to thecollector 86. A radial outlet 97 conduit extends from the collector 86for provision of a flow of air 98 from the impeller.

The blower 80 comprises a top housing portion (“upper housing”) 81comprising a plate 82 with a central air inlet aperture 82 a (see FIG.10, 11), and ribs 82 b extending radially across the plate across thecentral air inlet aperture 82 a to a hub. The ribs 82 b are shownexposed in FIG. 11. Alternatively, the ribs 82 b can be skewed 200 atthe central hub 200, as shown in the alternative embodiment in FIG. 13A.The skewing reduces the interaction with the blades of the impeller. Inthe particular embodiment illustrated in FIG. 13, each of the ribscomprise a radial portion and a skewed portion. Each skewed portionextends along an axis that is transverse to a longitudinal axis of itsrespective radial portion. Each radial portion extends from a peripheryof the plate to an outer edge of the central hub and each skewed portionextends from the outer edge of the central connecting portion whichconnects to all of the other skewed portions. An opening is formedbetween each adjacent skewed portion for air flow into the motor. Inother embodiments, the skewed portions of each of the ribs 82 could becurved at the central hub region to minimise interaction with theimpeller blades. FIGS. 11 and 13A-13C show 5 ribs, however, it will beappreciated there may be various numbers of ribs provided for example 3,5 or 9 ribs. It may be advantageous to have an odd number of ribs toensure the ribs provide a stable support base for the hood 83. As can beseen in FIGS. 11 and 13A-13C the ribs 82 b may be arranged in anequiangular manner. The upper housing 81 may further comprise engagementfeatures configured to orient and/or attach the upper housing 81 to thehood 83.

As can be seen from FIG. 11, the plate 82 can be coupled to thecylindrical side 85 a with a bayonet coupling 201, although friction fitor other couplings can be used. A hood 83 sits on the ribs. The ribs 82b set the hood 83 away from the plate to allow an air path 99 into theair inlet aperture 82 a so air can reach the impeller 95. Air flow 9goes into the inlet during use. The ribs 82 b also extend to and supporta central top hub 84 within the central aperture 82 a, the top hub alsocomprising a central aperture 84 a.

A motor assembly 88 is assembled into the inner motor region 87. A motorstator support 101 is arranged into an annular opening of the motorregion 87 to form a base of the motor 88 sub-housing. The motor statorsupport 101 has a profiled annular perimeter 101 a that sits in acorresponding annular rebate/shelf 86 c in the inner collector wall 86a. The motor stator support 101 also has a plurality of ribs 101 bextending radially from an annular perimeter 101 c to a bottom hub 101 dwith a central aperture 101 e housing a bearing race 110. As previouslydescribed top hub 84 is supported from the ribs of the hood, also with acentral aperture 84 a housing a bearing race 110. The bearing races canbe as previously described in the previous embodiments. In alternatives,a plane bearing or bushing could be used instead. A shaft 111 issupported between the top 84 and bottom hubs 101 d within the respectivebearing races 110 and extends from the top hub 84 through the centralaperture 92 of the central plate 91. The shaft is solid, althoughalternatively could be hollow, or partially hollow, as will be describedlater. Stub axles 112 on either end of the shaft 111 support the shaftin the respective bearings 110. The annular perimeter of the motorstator support also has a cylindrical side wall 101 f forming a region114 for concentrically supporting an annular/toroidal motor stator 89comprising an annular stacked laminated core 89 a with a toroidalwinding 89 b. An annular/toroidal magnet 90 is supported concentricallyon the shaft 111 and resides concentrically within the motorstator/motor stator region. An impeller 95 is supported on the shaft 111and housed within the impeller region 94 of the body 85. The impeller 95can be any of those previously described. The impeller can be coupledonto or integrally formed with the shaft 111. The shaft 111 can be ofsimilar diameter to the shaft in traditional topologies, which allowsfor robust mechanical coupling of the impeller.

In operation, the impeller spins and draws air through the centralaperture and passes it down around the annular gap into the volume andout the radial outlet.

This embodiment has the same advantages as described for the previousembodiments.

The shaft 111/stub axle 112/bearing 110 arrangement of this embodimentis the reverse arrangement of the previous embodiments. Rather than thebearings 110 being supported in the shaft 111, and the stub axles 112being supported in the upper/lower housing or hubs, in this embodimentthe stub axles 112 are on the shaft 111 and the bearings 110 are in thetop 84 and bottom 101 hubs.

Each of the stub axles extend to a distal end from respective upper andlower ends of the shaft. The stub axles extend away from each other.Each of the stub axles are substantially cylindrically shaped. In otherembodiments, one or both of the stub axles taper or decrease in diameteras they extend away from the respective upper and lower ends of theshaft. The distal end of each stub axle is rounded. However, in otherembodiments, the distal end of one or both of the stub axles issubstantially flat. Each stub axle also comprises a shoulder that isformed by a flange or stepped portion. In other embodiments, theshoulder formed by a taper in the stub axle. The shoulder is located ator near a proximal end of each stub axle to the shaft. Upper and lowerbearings engage the shoulder or respective stub axles to limit axialmovement of the bearing arrangement towards the shaft. Each of the top84 and bottom 101 hubs has a shoulder in an opposed relationship to eachrespective stub axle shoulder. Each hub shoulder is formed as a recessor stepped portion in an internal surface of the hub. In otherembodiments, the hub shoulder is formed by a taper in the internalsurface of the hub. The upper and lower bearings also engage respectivehub shoulders so that they are gripped between a shoulder on arespective hub and a shoulder on a respective stub axle.

In all embodiments, the arrangement is such that a bearing and stub axlearrangement couples the shaft to upper/top and lower/bottom supports ofthe blower. The bearings and shaft can otherwise have similarconfigurations (although in this embodiment the shaft need not behollow), and as such this arrangement still provides the same benefitsas the previous embodiments. The shaft can be of similar diameter to theshaft in traditional topologies, which allows for robust mechanicalcoupling of the impeller. But, because the stub axles can be thinnerthan the shaft and extend into the bearings, the diameter of the shaftis not dictated by the inner diameter of the bearings. The outerdiameter of the shaft can then be a suitable size to allow for a robustimpeller coupling, e.g. about 5 mm, or alternatively from about 3 mm toabout 5 mm A larger diameter shaft can still be used without dictatingthe bearing diameter size, because the bearings are off the shaft. Thesize of the bearing (e.g. the diameter size) can therefore be selectedbased on acceptable bearing speed. Similarly, the magnet/rotor 17/17 ais pressed into the shaft. Similar advantages apply here, where theshaft can be a suitable size to allow for robust coupling.

The embodiments above show some examples of the shaft, stub axle andbearing arrangement that provide the advantages of the presentinvention. However, these embodiments are not exhaustive. Moregenerally, it will be appreciated that other embodiments are alsopossible, with any combination of the following configurations:

-   -   bearings in the shaft, or alternatively bearings on the        top/bottom support    -   stub axles in the top/bottom support, or alternatively stub        axles on the shaft    -   hollow, partially hollow, or solid shaft.

As an example, and referring to FIG. 12A, in some embodiments, theblower has a hollow shaft 27, bearings 28 at either end of the shaft,and stub axles 29 a, 29 b on the top/bottom support.

As another example, and referring to FIG. 12B, in some embodiments, theblower has a solid shaft 111, stub axles 112 on either end of the shaft111, and bearings 110 on the top/bottom support. As illustrated in FIG.12B, the stub axles 29 a, 29 b in the impeller are rigid and thetop/bottom supports have a resilient “cup” 220 to accept the bearing.The resilient material of the cup 220 is thin, and is just visible inthe cross-section view. Alternatively, as previously described, the stubaxles 29 a, 29 b are made of resilient material.

As another example, and referring to FIG. 12C, in some embodiments, theblower has a partially hollow shaft 210, bearings 28 at either end ofthe shaft, and stub axles 29 a, 29 b on the top/bottom support. In theseembodiments, the shaft has recesses formed in each end of the shaft. Thebearings and stub axles are at least partially received withinrespective recesses of the shaft.

The embodiments above show various configurations of inlet/outlettopologies. Various combinations of inlet and outlet topologies could beincorporated into any of the above described embodiments. For example,in some embodiments, as shown in FIGS. 13A, 13B, the blower could havean axial inlet A/axial outlet B topology (the ribs 82 b being differentin each case). In other embodiments, as shown in FIG. 11, the blowercould have an axial inlet A/radial outlet B/97 topology. In otherembodiments, as shown in FIG. 13C, the blower could have an axial inletA/tangential outlet C/230 topology.

Other topologies of motors are possible, and those described areexemplary only. For example, a brushed or brushless DC motor, AC motor,inductance motor or variable reluctance motor could be used. The rotorand motor stator could take other forms to that described.

The embodiments described have a number of advantages. They provide areduced footprint blower, both in profile and/or plan. A smaller footprint allows for a smaller housing. One reason for the smaller footprint is that the airflow stator ring allows a volute to be omitted,reducing overall diameter of the blower, and also increasing the ratioof blade length to housing diameter (that is, the space for blade lengthis not reduced due to the presence of a volute allowing the blade lengthto use more of the available footprint diameter than a housing with avolute).

The embodiments also allow for the use of a smaller impeller (that is,smaller in diameter thickness and/all weight). This in turn leads to asmaller/lighter blower and/or a blower with a lower inertia. Asmaller/lighter topology enables the blower to be used in portable,miniaturised and/or head or mask mounted CPAP, high flow therapy orother breathing apparatus.

As an example, the impeller might have a diameter of about 47 mm insidean about 48 mm diameter ring provide a ratio of blade length to housingdiameter of 98%. Another example is about 18 mm blades in an about 20 mmradius housing for a 90% ratio. These are just illustrative examples andother diameters are possible. A typical envelope/footprint of the blowercould be:

-   -   Diameter: <=about 53 mm    -   Height: <=about 21 mm    -   Weight: <=about 50 grams, or <=about 47 grams (for example 27        grams)

Optionally the impeller has:

-   -   a thickness of less than or equal to about 3 mm    -   a diameter of less than or equal to about 48 mm, or more        preferably 48.4 mm    -   a weight of less than or equal to about 3 grams

Other dimensions will become apparent upon reading this description.Maximising the blade to housing ratio is preferred.

Small impellers of these dimensions have not been suitable for use inthe applications described above. This is because, when operated at theusual speeds (revolutions per minute), the air flow characteristics areinsufficient to provide required therapy (for example, the flow rateand/or pressure generated by smaller impellers of this nature are notsufficient). Further, it has not been possible to run these impellersare high speeds to create the required flow rates and/or pressures,because those speeds create a number of disadvantages. For example, withincreased speed, the bearings operate at a higher speed and/ortemperature. This requires the use of special bearings, such as ceramic,air or fluid bearings, which are more expensive. Smaller diameterbearing races and bearings need to be used to reduce the speed of thebearings. This leads to a necessary drop in the shaft diameter, so thatthe shaft can still go through the centre of the bearing race. Whenusing a smaller diameter shaft, it is much more difficult to attach theimpeller and/or rotor magnet, for example through integral design or afriction fit. The manufacturing tolerances are too precise for this tobe done in a viable manner. Therefore, accommodating a smaller impellerup to now has been impracticable. Another alternative is to use a blowerwith multiple impeller stages, however that is more expensive, largerand is more difficult to manufacture.

The present embodiments overcome these issues and allows for the use ofa smaller impeller in a single-stage blower. The shaft that is used ishollow, or at least partially hollow. Bearings are fitted to the insideof the shaft. This allows for two things. First it allows for the shaftdiameter to be of the same or similar size as previously, so that animpeller and/or rotor (or magnet) can be integrated into or fitted to ashaft in the usual manner; and second because the bearings are disposedinternally, it allows for smaller diameter bearings (while still havingthe same is diameter shaft) to be used. This then allows the impeller tobe spun at higher speeds to create the required flow rate and/orpressure with a smaller diameter impeller. But, despite theimpeller/shaft being run at higher speeds, the smaller diameter bearingsrun at a lower circumferential speed (or a higher angular rate) thanwould larger diameter bearings traditionally used, which avoids theproblems with higher speeds mentioned above. The stub axles thereforeallow for connection to the internal races of the bearings, and thecompliance/resilience of the stub axles allow for compliance when theshaft spins. The arrangement also reduces or eliminates eddy currents inthe shaft and/or bearings. The eddy currents can degrade the bearings.

In addition, the stub blades and increased air inlet numbers and/or sizeallow for more pressure to be generated from a smaller blade length.

The axial outlet eliminates the need for a tangential outlet duct, whichcan increase the blower footprint.

The arrangement also allows for a single stage axial input/axial outputblower, which provides for a reduced footprint or lower (low) profile.The embodiment described does not have a volute which reduces the sizealso. The airflow stator ring creates static pressure. The axial airflowinlet allows for motor stator cooling.

1-22. (canceled)
 23. A blower for a breathing apparatus comprising: abottom support for a shaft, a top support for a shaft, a motor corecomprising a stator and rotor an impeller coupled to the motor core viaa shaft wherein the shaft is rotatably coupled at a first end via a stubaxle and bearing arrangement to the top support and at a second end viaa stub axle and bearing arrangement to the bottom support.
 24. A blowerfor a breathing apparatus according to claim 23 wherein the shaft isrotatably coupled at the first and second ends to the stub axles bybearings in the shaft.
 25. A blower according to claim 23 wherein theshaft is rotatably coupled at the first and second ends to the top andbottom supports by stub axles and bearings in the top and bottomsupports.
 26. A blower according to claim 23 wherein the stub axle iscompliant and/or resilient.
 27. A blower according to claim 23 whereinthe shaft is partially or fully hollow and the first and second endshave bearings within the hollow.
 28. A blower according to claim 23wherein each bearing comprises an inner race and an outer race, and eachstub axle couples to the respective inner bearing race.
 29. A bloweraccording to claim 23 wherein each stub axle is in the form of aprotrusion that extends into and couples to the respective inner bearingrace.
 30. A blower according to claim 23 wherein each stub axle isformed from an elastomer.
 31. A blower according to claim 23 whereineach stub axle is configured to have a friction fit within therespective inner bearing race.
 32. A blower according to claim 23wherein one or more of the stub axles comprises a shoulder that isformed by a flange, stepped portion or a taper.
 33. A blower accordingto claim 23 wherein one or more of the stub axles comprises an overmoulded compliant and/or resilient material.
 34. A blower according toclaim 23 wherein one or more of the stub axles are formed from anelastomer.
 35. A blower according to claim 23 wherein the shaft maximumdiameter size is independent of the bearing diameter size.
 36. A bloweraccording to claim 23 wherein the blower is an axial inlet/axial outletblower.
 37. A blower according to claim 23 wherein the blower is asingle stage axial inlet/axial outlet blower.
 38. A blower according toclaim 23 wherein the blower is an axial inlet/radial outlet ortangential outlet blower.
 39. A blower according to claim 23 wherein theblower is a single stage axial inlet/radial outlet or tangential outletblower.
 40. A blower according to claim 23 wherein the impeller isintegrally formed with the shaft or is coupled via a press-fit, overmoulding or glue.
 41. A blower according to claim 23 wherein the rotoror magnet is press-fit on the shaft or coupled via over moulding orglue.